Apparatus for injecting sand beneath submerged constructions

ABSTRACT

Apparatus for injecting sand under a construction or excavation in the water in which the construction is temporarily suspended or rests on temporary supports comprising combined feed and suction pipes each having a branch adapted to extend beneath the construction and a branch extending vertically above the surface of the body of water; means for reciprocating or oscillating the branches beneath the construction and including a feedpipe through which a mixture of sand and water can be pumped into the space below the construction, and at least one suction pipe through which a corresponding quantity of water can be extracted or withdrawn from the space into which sand and water are being deposited, and at least a flushing feedpipe through which water can be forcibly ejected to flush suspended or partially deposited lightweight materials.

United States Patent inventor Kai Havno Copenhagen, Denmark Appl. No. 831,302

Filed June 9, 1969 Patented May 4, 1971 Assignee Christiani & Nielsen A/S Copenhagen, Denmark Priority June 18, 1968 Denmark 2854/68 APPARATUS FOR IN] ECTING SAND BENEATH SUBMERGED CONSTRUCTIONS 4 Claims, 3 Drawing Figs.

US. Cl 61/63, 61 /35, 61/50 int. Cl E02d 3/12, E02d 27/00 Field of Search 61/63, 50,

[56] References Cited UNITED STATES PATENTS 2,191,845 2/1940 Bretting 61/63 3,l63,448 l2/ 1964 Franklin 138/ l l2X Primary ExaminerJacob Shapiro Attorney-Karl W. Flocks ABSTRACT: Apparatus for injecting sand under a construction or excavation in the water in which the construction is temporarily suspended or rests on temporary supports comprising combined feed and suction pipes each having a branch adapted to extend beneath the construction and a branch extending vertically above the surface of the body of water; means for reciprocating or oscillating the branches beneath the construction and including a feedpipe through which a mixture of sand and water can be pumped into the space below the construction, and at least one suction pipe through which a corresponding quantity of water can be extracted or withdrawn from the space into which sand and water are being deposited, and at least a flushing feedpipe through which water can be forcibly ejected to flush suspended or partially deposited lightweight materials.

PATENTED w m.

INVENTOR KAJ HAVNQ' BY 62L w hock;

ATTORNEY APPARATUS FOR INJECTING SAND BENEATI-I SUBMERGED CONSTRUCTIONS When sand is to be injected under building constructions submerged in water it is a known practice to use an arrangement of angled pipes, to lower substantially horizontal branches of which a reciprocating swing in an arc of a circle is imparted within the boundaries of a space between a construction temporarily suspended or resting on temporary supports, while simultaneously water mixed with sand is pumped in under the construction through one of the pipes of the arrangement simultaneously with extraction of a corresponding amount of water through other pipes of the system. In this way, the sand does not eddy nor is washed away, but is deposited densely in a wall shaped as an arc of a circle about an axis formed by the axis of the reciprocating or oscillating pipe arrangement. By moving vertical branches of the pipe arrangement along one side of the construction, the space under the construction may be filled with a wall of sand of uniform density with a uniform pressure against the underside of the construction. The vertical branches of the pipe arrangement extend upwardly to above the surface of the water and are connected to pumps which pump the mixture of water and sand through a pressure pipe and simultaneously extract a corresponding amount of water through suction pipes while a swinging motion is imparted to the pipe arrangement.

In rivers and streams fine-grained materials such as silt, suspended clay or like materials, are partly kept suspended by the current, but are deposited particularly at places where the current slows down. In an excavation for a construction the fine materials tend to be deposited in a stratum of a low specific gravity and poor load-bearing characteristics. Such stratums, must therefore, be removed before a load-bearing stratum of sand can be deposited. If after submersion of a construction onto a temporary support the stratum of sand is not filled in quickly enough, the space under the construction may become filled or partly filled with mud which, particularly after passage of time, consolidates to a low strength but has a considerable specific gravity, yet without being able to be used as a load-bearing foundation, and which is difficult to remove from the narrow space under the construction, unless the construction is raised again and the foundations reexcavated.

Accordingly, primary objects of the present invention are to provide an apparatus for injecting sand under a construction submerged in water and temporarily suspended or resting on temporary supports, comprising a combined feed and suction pipe unit formed by a plurality of pipes each having one branch adapted to extend under the construction and another branch adapted to extend upwardly to above the surface of the water, means for imparting a reciprocating swing to the branches adapted to extend under the construction; the pipe unit including a feedpipe through which a mixture of sand and water can be pumped into the space below the construction, which constitutes an improvement to the effect that the apparatus will also, in a simple manner, be able to remove silt from the space below the construction in that at least one suction pipe through which a corresponding quantity of water can be extracted from said space and at least one flushing feedpipe through which water can be fed to said space to flush lightweight materials therefrom.

Another object is to provide apparatus to flush in material or remove same, or another material, from the space below a submerged construction supported a little above the bottom of an excavation.

Another object is to provide an apparatus which may be used both as an excavation apparatusfor digging out silt or other undesired material and for, immediately after the excavation, filling in sand under the construction, so that another undesired deposit of mud is prevented.

A further object is to provide flushing apparatus in which a pipe system includes feedpipes of different lengths in a horizontal branch which is extended under a construction, and in some cases in which a pressure pipe of a flushing pipe system may be used together with feedpipes of a filling system adapting the latter in such a manner that instead of pumping a mixture of water and sand, as in the case when operated for filling in beneath the construction, it may be operated to pump water under pressure.

Alternatively, a further object is to provide three flushing feedpipes comprising one central feedpipe having a portion extending under a construction substantially the same length as the portion of feedpipe, and two side flushing feedpipes, one on each side of the central pipe, and the latter two having a portion extending under the construction a length substantially less than the length of that portion of the central pipe.

A further object is to provide in the apparatus as set forth, side flushing feed pipes in which the pipes are formed with conical nozzles at their terminal ends for obtaining .high velocity pressure thereat.

Further, an object is to supply water through a flushing pipe system simultaneously with suction and obtaining an effect which is quite opposite to that normally resulting in filling apparatus; without stirring or mixing water and material deposited therein and/or forming eddy currents under the construction, and substantially removing material deposited in an excavation before foundation sand is deposited beneath a construction.

The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which:

FIG. 1 is a fragmentary side elevation view;

FIG. 2 is a top plan view of FIG. 1; and

FIG. 3 is a front elevation view looking from right to left of FIGS. 1 and 2.

In the embodiment shown, the feed and suction pipe arrangement comprises a pressure feedpipe 1 connected to a pump, not shown, for the supply of water and sand and two extraction or suction pipes 2 each including to an air-lift pump, the lower end 3 of which is shown, and compressor tube 4 thereof. The pipes l and 2 are bent so that they each have a horizontal and a vertical branch. The system of feedpipe l and extraction pipes 2 is the now-classic system for filling in sand under a submarine construction suspended over the bottom of the sea, a lake or a river. A flushing feedpipe system of the arrangement comprises a flushing feedpipe 5, having its horizontal branch situated below the pressure feedpipe 1, and two side flushing feedpipes 6 which at the ends opposite to their free ends are united into one vertical pipe 7.

The flushing feedpipe 5 has its horizontal branch the same length as the horizontal branch of the feedpipe 1 of the filling system, but the horizontal branch of the flushing feedpipes 6 are considerably shorter. These short pipes have at their free ends conical nozzles 8 for increasing the speed of the water flowing out of the pipes 6.

When the space under a big building construction is to be cleaned from deposited material, the horizontal branch of the apparatus is inserted under the construction and water is fed simultaneously through the pipes 1, 5 and 6. At the same time a strong suction is effected by the two suction extraction pipes 2. The water thus fed under pressure will loosen the deposited material and cause it to be mixed with the water, and the mixture will be drawn back through the suction extraction pipes 2.

In some cases the flushing feedpipe 5 of the subpipe system may be omitted and only the flushing feedpipe 1 of the filling system be used.

It will be obvious to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown in the drawings and described in the specification.

I claim:

1. Apparatus for injecting sand beneath a body of water and under a construction submerged in the water and/or temporarily suspended or resting on temporary supports, the apparatus comprising a combined feed and suction pipe unit including a plurality of pipes each having one branch adapted to extend beneath the construction and another branch adapted to extend upwardly to above the surface of the body of water,

means connected to said branches for moving the branches beneath a construction, the unit including a feedpipe for receiving a mixture of sand and water pumped therethrough and below the construction, and at least one suction pipe connected to pump means for drawing off a quantity of water corresponding to the volume of water and sand introduced by the other pipe, and at least one flushing feedpipe extending below the combined feed and suction pipe unit and operably communicating with a pressure source adapted to supply water through said at least one flushing feedpipe, which water can be fed to the space to flush and stir up lightweight materials.

2. The structure as claimed in claim 1 in which the unit comprises three flushing feedpipes including one central flushcal nozzles at their free ends.

4. The structure as claimed in claim 1 including an apertured plate through which pipes of the unit are transversely disposed for maintaining the pipes in a fixed relation with respect to each other. 

2. The structure as claimed in claim 1 in which the unit comprises three flushing feedpipes including one central flushing feedpipe having a portion adapted to extend beneath the construction, and two side flushing feedpipes flanking the central flushing feedpipe, the side flushing feedpipes having a length substantially less than the central flushing feedpipes.
 3. The structure as claimed in claim 2 in which the central feedpipe and the side flushing feedpipes include terminal conical nozzles at their free ends.
 4. The structure as claimed in claim 1 including an apertured plate through which pipes of the unit are transversely disposed for maintaining the pipes in a fixed relation with respect to each other. 